This invention concerns a harvesting or gathering platform having an in-line knife drive and especially to a mounting bracket for the drive motor which assures proper alignment of the drive motor with the knife.
Harvesting platform knives have typically been driven by a gearbox having a rotating output shaft. The gearbox, or drive motor, output shaft is coupled to the knife by a drive arm. The output shaft rotates back and forth to produce an arcuate reciprocating motion to the end of the drive arm. As a result, the knife does not move in a purely linear motion. The knife end moves in the arcuate path of the drive arm, resulting in the knife end moving in an arcuate path as the knife reciprocates. The arcuate movement of the knife end causes a sine wave deflection of the knife to travel along the length of the knife. This deflection is more pronounced in a double cut knife where the knife stroke is longer, thus requiring greater rotation of the drive arm. One solution is to lengthen the drive arm. This reduces the angular extent of rotation of the motor output shaft needed for the longer stroke. A longer drive arm, however, presents other difficulties.
Another solution to the arcuate motion in the knife is to provide a knife drive that is linear. Such a linear drive is available from the Schumacher Company of Germany and is described in U.S. Pat. No. 4,813,291. This drive has a rotary input device, such as a pulley or gear, and an output shaft that reciprocates in a linear motion, normal to the axis of the output shaft. Such a drive is referred to as an "in-line" drive. With an in-line drive, it is necessary to properly position the drive motor output shaft so that the direction of motion of the output shaft is in-line with desired knife motion.